Scene exposure where there’s black-blacks, white-whites and a mid grey subject?

The scene contains high key highlights (a X/10 on Ansell’s System PLUS Black (0 on Ansell’s).

Your subject – a mountain – is a mid range (5 – Ansell again).

To get the best exposure in the photograph you spot meter (with a handheld meter) say the 10, the 0 and the 5.

Meter Readings:
0 = 125 at f1.4
10 = 125 at f8
5 = 125 at f4

(For this discussion, I’m ignoring my camera and the matrix meter mode, as I am learning about handheld meters to hopefully get a better outcome and more often.)

Questions: I ‘hear’ that one combines these three figures, in some fashion, and takes the square root of the same?
If this is correct? Whats the best method to ensure correct exposure, as best as possible, for the entire scene? Or is this simply not possible?

Cheers and Thanks
Greg Jorgensen